Increased isobutanol production in Saccharomyces cerevisiae by overexpression of genes in valine metabolism

Table 1 Effects of gene overexpression on growth rates and product yields under anaerobic batch fermentations^a

Strain	Reference strain^b	*ILV2 ILV3 ILV5* overexpression strain^b	*ILV2 ILV3 ILV5 BAT2* overexpression strain^b	*ILV2 ILV3 ILV5 ILV6* overexpression strain^b
Specific growth rate, per h	0.38 ± 0.02	0.29 ± 0.02	0.16 ± 0.01	0.18 ± 0.00
Biomass (CH_1.78O_0.6N_0.19) yield, g/g glucose	0.10 ± 0.00	0.11 ± 0.01	0.07 ± 0.01	0.11 ± 0.00
Ethanol yield, g/g glucose	0.38 ± 0.01	0.37 ± 0.02	0.34 ± 0.01	0.37 ± 0.00
Pyruvate yield, g/g glucose	0.0011 ± 0.007	0.0016 ± 0.0007	0.0032 ± 0.0006	0.0028 ± 0.0001
Succinate yield, g/g glucose	0.0016 ± 0.0006	0.0006 ± 0.0001	0.0028 ± 0.0001	0.0035 ± 0.0003
Glycerol yield, g/g glucose	0.100 ± 0.008	0.087 ± 0.006	0.095 ± 0.001	0.099 ± 0.003
Acetate yield, g/g glucose	0.0076 ± 0.0014	0.0088 ± 0.0010	0.0110 ± 0.0006	0.0069 ± 0.0003
CO₂ yield, g/g glucose	0.32 ± 0.01	0.39 ± 0.01	0.37 ± 0.04	0.41 ± 0.03
Carbon balance deviation,%^b	5.9 ± 2.2	3.0 ± 4.0	10.9 ± 1.7	1.3 ± 1.7

^aThe mineral medium with 40 g/l of glucose was used.
^bThe reference strain used was CEN.PK 113-5D; The ILV2 ILV3 ILV5 overexpression strain used was ILV235_XCY561; The ILV2 ILV3 ILV5 BAT2 overexpression strain used were ILV235BAT2_XCY715 and ILV235BAT2_XCY723; The ILV2 ILV3 ILV5 ILV6 overexpression strain used was ILV2356_XCY605.